1. Field of the Invention
The present invention relates to AC high voltage power supply devices, charging devices, developing devices, and image forming apparatuses, and more particularly to an AC high voltage power supply device for generating an AC high voltage, a charging device and a developing device including the AC high voltage power supply device, and an image forming apparatus including at least one of the charging device and the developing device.
2. Description of the Related Art
A method typically performed by an image forming apparatus such as a printer, fax machine, a copier, or a multifunction peripheral including these functions, includes the steps of charging a photoconductive drum with the use of a charging device, and scanning the surface of the charged photoconductive drum with laser light modulated in accordance with image information to form an electrostatic latent image on the surface of the photoconductive drum.
Furthermore, with the use of a developing device, toner is caused to adhere to the electrostatic latent image formed on the surface of the photoconductive drum to form a visible image (develop the latent image), which is transferred onto a recording sheet.
The above described charging and developing operations typically use a voltage obtained by superposing an AC high voltage and a DC high voltage. Thus, an image forming apparatus typically includes an AC high voltage power supply device for generating an AC high voltage (for example, see patent documents 1 through 4).    Patent Document 1: Japanese Laid-Open Patent Application No. 2001-117325    Patent Document 2: Japanese Laid-Open Patent Application No. 2001-312123    Patent Document 3: Japanese Laid-Open Patent Application No. 2007-171936    Patent Document 4: Japanese Laid-Open Patent Application No. 2007-199377
However, in conventional AC high voltage power supply devices, large power loss is caused by heat generated in the amplifier circuit, which leads to increased power consumption. Furthermore, a large radiator plate is necessary for mitigating temperature increases, and therefore it is difficult to reduce the size of the device.